You will have to apply for visa at the US embassy or consulate. Your son cannot take you to the US. When he turns 21, he can petition you for immigration. Before that, you will have to find a reason to apply for visa (such as B2 for tourist, H1 for working for a US employer, F-1 for study, etc.).
Answered on Oct 28th, 2011 at 7:27 PM